1. Field of the Invention
The present invention relates, in general, to control circuits for Light Emitting Diode (LED) illumination devices, and more particularly to an economical, low-voltage dimmer control configured for use in a standard electrical box of the type typically used, for example, in residential lighting installations, for controlling the brightness of LED lamps.
2. Discussion of the Prior Art
Traditionally, LED illumination devices have been used as low power indication devices and for low power electronic displays, principally because they were small and long-lasting, and because they used very small amounts of power as compared to incandescent bulbs, neon tubes or other light sources. As materials science and semiconductor fabricating technologies progressed, it became feasible to manufacture LEDs that would generate an increased amount of light per device (i.e., having greater luminous intensity, or brightness) in a wider variety of colors, with the result that LED lighting has recently found applications in a variety of new areas. Since LEDs more efficiently convert electrical energy into visible light and because the energy usually wasted as heat is much lower for LEDs than for most other sources of light, LED lights are between 5 and 10 times more efficient than incandescent lights, and about 2 to 3 times more efficient than fluorescent lights.
Recently, it has become economically feasible to make relatively high output LEDs which render a pleasing white light, and these newer LEDs have been incorporated into automotive and traffic signaling lamps, handheld flashlights and a variety of other products. In addition, LED lamps have become viable for use in residential and other illumination fixtures, and they can now be obtained in a configuration having a standard Edison-style base for use, for example, in an ordinary lamp socket configured for standard incandescent bulbs.
The particular characteristic of the LED which remains unchanged by these recent developments, however, is that, being a solid-state Diode, it typically has only two states; namely, “on” or “off.” Therefore, users seeking to adjust the illumination from an LED lamp were confounded by this characteristic, and those who wanted a light that could be controlled with a standard “dimmer” were frustrated, because the common technique for dimming incandescent bulbs by lowering the supply voltage, when applied to an LED lamp typically would only turn the lamp from “on” to “off”.
Standard dimmers are readily available to consumers for use in “single-gang” electrical boxes, where they are often installed instead of a standard single-throw light switch in residential and commercial lighting applications. The space in that single gang box is limited, however, since it is about 1.50″ wide, 2.25″ long and 1.25″ high, and there is no way, at present, to provide a dimming control at suitable power levels for driving LED lamps, where the dimming control circuitry will fit in such a tight spot, for prior approaches were cumbersome and expensive.
Some of the newer LEDs can be powered directly from a 120V supply line, but these tend to be expensive and many of them cannot be dimmed, and when used in ambiance lighting, they have the tendency to be too bright. LEDs using lower voltage levels are more economical, but the circuitry used to switch or modulate a voltage signal has typically required too much power, generated too much heat and taken up too much space to be useful for anyone but a technician who has the space and budget to assemble the power supply and pulse width modulating or switching components needed to generate a useable dimming signal. There is a need, therefore, for an economical and easy to use low voltage LED dimmer controller for overcoming these problems, and providing an economical and convenient-to-install structure which can work in typical residential lighting installations.